Changes in the microbial population of the gastrointestinal tract may underlie some of the benefits of gastric bypass surgery, reports a team of researchers from MGH and Harvard University. The investigators also found that post-bypass alterations in the microbial population of mice can induce weight loss in animals that did not have surgery.

MGH researchers have identified a gene variant that helps predict how much weight an individual will lose after gastric bypass surgery, a finding with the potential both to guide treatment planning and to facilitate the development of new therapeutic approaches to treating obesity and related conditions like diabetes.

New findings about the mechanisms involved – or not involved – in the effects of the most common form of bariatric surgery suggest that combining surgery with a specific type of medication could augment the benefits of the procedure.